The present invention relates to a vehicle clutch control device.
As is known, when releasing and engaging the clutch, e.g. when changing gear and starling the vehicle, the torque transmitted from the engine to the drive wheels via the clutch mainly depends on the load acting on the clutch disk, which in turn depends on the position of the clutch control lever.
The clutch is normally operated manually by the driver of the vehicle, who controls engagement of the clutch to transfer the torque via the clutch substantially gradually so the vehicle runs smoothly.
The clutch can also be operated fully automatically by means of electronic control devices, which, when operating the clutch, control the position of the clutch control lever according to a number of input signals.
Known control devices normally comprise an electronic central control unit, which receives control signals and controls release/engagement of the clutch by means of a solenoid valve supplied with pressurized fluid by a hydraulic circuit and which, on the basis of the incoming signals, operates an actuator connected to the clutch.
Control devices also comprise a position sensor connected to the actuator and generating a feedback signal related to the operating position of the actuator; and a control circuit installed in the electronic central control unit and supplied with the feedback signal, on the basis of which a control signal is supplied to the solenoid valve.
More specifically, the control circuit comprises a computing circuit, which receives a number of information signals (i.e. quantities, such as accelerator pedal position, engine speed, clutch speed, brake pedal position, etc.) and supplies a reference signal indicating the position of the clutch.
The control circuit also comprises an adding circuit, which receives the feedback signal from the position sensor and the position reference signal, and supplies an error signal to an input of a controller (e.g. PID proportional-integral-derivative) circuit, which in turn supplies the solenoid valve control signal to operate the clutch actuator.
A major drawback of known control devices is that, in the event of a fault on the position sensor, the control circuit is supplied with an erroneous feedback signal, thus resulting in an incorrect control signal being supplied to the solenoid valve.
As a result, operation of the actuator becomes erratic, difficult and/or impossible, and poses obvious safety hazards caused by failure to release/engage the clutch.
It is an object of the present invention to provide a vehicle clutch control device designed to control the clutch actuator assembly even in the event of a fault on the position sensor.